On the Origin of the Brain Semi‐Heavy Water Deuterium <scp>MR</scp> Signal Following Administration of Deuterated Metabolic Substrate: A Cautionary Tale

Body production of HOD dominates the initial increase of HOD in brain following administration of [6,6-²H₂]fructose and likely contributes significantly to the increase of HOD in brain following administration of [6,6-²H₂]glucose. Interpretation of HOD concentrations as representative of organ-specific metabolism requires careful consideration of control experiments and assessment of HOD contributions from body metabolism of the administered deuterated substrate.